Effect of dietary ecdysterone on protein ingestion and copulatory behaviour of the blowfly, Sarcophaga bullata

ABSTRACT. In Sarcophaga bullata and other blowflies, the low haemolymph ecdysteroid titre is responsible for the inability of males to synthesize vitellogenin, although they have the genes coding for this protein. The high moulting hormone titre in females is of crucial importance for vitellogenesis. In this context we investigated whether the difference in protein ingestion between the sexes might also be related to differences in ecdysteroid titre. Using a two-choice system, we observed that upon addition of ecdysterone to the food, protein ingestion increased in males. Topical application of methoprene also had a stimulating effect. Prolonged treatment with ecdysterone reduced the copulatory behaviour of males.